The present invention relates to a ball bearing.
A prior art ball bearing such as a radial ball bearing has an inner ring formed in its outer periphery with a ball guide groove, an outer ring formed in its inner periphery with a ball guide groove, a plurality of balls received in the guide grooves formed in the inner and outer rings, and a retainer for keeping the balls circumferentially apart from one another.
It is comparatively easy to grind a ball guide groove in the outer periphery of the inner ring of such a prior art ball bearing by use of a grinder, because the diameter of the grinder is not limited. But it is extremely difficult to precisely grind a ball guide groove in the inner periphery of the outer ring especially if the bearing is a small-sized one. This is because in order to grind such a groove the grinder has to have a smaller diameter than the inner diameter of the outer ring. Another disadvantage is that such a small-diameter grinder with a short peripheral length tends to wear rapidly.
To assemble such a ball bearing, the outer ring is moved to an offset position with respect to the inner ring to create a wide gap between the rings at one side, the balls are set in the gap, the outer ring is brought back into alignment with the inner ring, and finally the retainer is mounted to hold the balls spaced apart from one another. Such complicated assembling steps increase the production cost.